Does My Roof Have The Correct Fall ? (BS 6229)

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looking for some advice regards the fall on my recently done grp roof. I am aware that under BS 6229  there is a requirement for a certain amount fall ( 1:80 to account for ponding etc, to be honest I've no idea how to confirm wether or not my roof meets the minimum fall.
My roofer is not the easiest person to deal with and just says its fine, give me my money. The roof is 2310mm deep, there are a number of areas that have dips even though its all new osb, lots of ponding and standing water.

I've put a level on it and from front to back there's a 30mm difference. From the little I've manged to pick up from here and google etc I suspect the difference should be in the region of 50mm, I would be most grateful if anybody could offer some advice.



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best practice is to aim for minimum of 1:40 in construction, to achieve 1:80 in reality.


to work out what 1:80 needs to be take the run (length of the roof) and divide by 80.


2310/80 = 29mm

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